Dry planographic printing plate

ABSTRACT

A laminated negative acting presensitized planographic printing plate for use in dry planography having 
     (a) a base layer. 
     (b) a silicone rubber layer overlying the base layer, and 
     (c) a photoadhesive layer overlying the silicone rubber layer comprising at least one photopolymerizable unsaturated compound having a boiling point above 100° C. and a photoinitiator. 
     Under exposure to light through a negative transparency, the photoadhesive layer polymerizes in the exposed image area and adheres to the underlying silicone rubber layer, while remaining non-adhesive to the underlying silicone rubber layer in the unexposed non-image area. 
     The unexposed photoadhesive layer only is removed to bare the underlying silicone rubber layer which is made an ink-repellent non-image area and the photoadhesive layer remaining in the exposed area is made an ink-receptive image area. 
     The surface of the photoadhesive layer accepts ink from inking rollers, while the silicone rubber background area will not remove ink from the rollers and thus remains ink free.

This is a continuation of application Ser. No. 514,063, filed Oct. 11,1974 now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to a negative-type planographic printingplate having ink-repellent silicone rubber in a non-imaged area and iscapable of printing in the absence of dampening.

Heretofore, several proposals have been made with reference to a dryplanographic plate having an ink-repellent layer of silicone rubber, allof which, however, have various deficiencies such as having inferiorstrength of the printing plate or presenting problems in developingmethod. For example, what is disclosed in Japanese patent publicationNo. 2361/1972 is a presensitized planographic printing plate providing aphoto-insolubilizable water soluble diazonium resin layer on the layerof silicone rubber. When a negative transparency is put on said plateand exposed to light and thereafter treated with aqueous developingliquid, the diazonium resin layer in the unexposed area dissolves toexpose the surface of the silicone rubber layer to form an ink-repellentnon-imaged area, whereas in the exposed area, the hardened diazoniumresin layer remains to form an ink-receptive image area. However, thereis insufficient adhesion between the diazonium resin layer in the imagearea and the underlying silicone rubber layer, and this deficiency ofthe planographic printing plate is such that the diazonium resin layerof the image area is peeled by inking rollers during printing or isremoved by careless scratch.

An object of the present invention is to overcome such deficiencies andto provide a negative-type planographic printing plate excellent inadhesive strength of the ink-receptive image area, surface strength ofthe printing plate, storability, scratch resistance and high durabilityin long run printing.

Another object of the present invention is to provide a negative-typeplanographic printing plate having excellent reproducibility of imageand broad permissible range of the exposing time.

SUMMARY OF THE INVENTION

The presensitized dry planographic printing plate in the presentinvention is a negative acting plate comprised of

(a) a base layer,

(b) a silicone rubber layer overlying the base layer, and

(c) a photoadhesive layer overlying the silicone rubber layer,comprising at least one photopolymerizable unsaturated compound having aboiling point above 100° C. and a photoinitiator.

Upon exposure to light through a negative transparency, thephotosensitive layer in the exposed image area polymerizes and adheresfirmly to the underlying silicone rubber layer, whereas thephotoadhesive layer in the unexposed non-image area remains non-adhesiveto the underlying silicone rubber layer.

Next, a planographic printing plate is produced in which thephotoadhesive layer is removed only in the unexposed area to bare theunderlying silicone rubber layer, the photoadhesive layer remaining inthe exposed area is made an ink-receptive image area and the siliconerubber layer in the unexposed area is made an ink-repellent non-imagearea.

The present invention has the following novel and importantcharacteristics. Upon irradiating actinic light through a negativetransparency to the printing plate, the photoadhesive layer in theexposed area not only polymerizes and cross-links to become insoluble,but also adheres to the underlying silicone rubber layer and cannot beeasily peeled off. As a result, the adhesive strength of theink-receptive image area of the resulting printing plate and eventuallythe strength of the plate surface is increased remarkably, and not onlyare the storability and scratch resistance improved, but also thedurability in long-run printing is strikingly increased. In this casephotoadhesion in the interface between the photoadhesive layer and thesilicone rubber layer has a very important significance, which isremarkably different from the hitherto known cases.

The flexible base substrate employed in the present invention should besufficiently flexible for mounting on a lithographic press and strongenough to withstand the load normally produced by the lithographicpress. Representative substrates include coated paper, metals orplastics such as polyethylene terephthalate. However, it is mostpreferable to use a substrate whose reflectivity to light of a wavelength of 300-400 mμ is not more than 20%, since the reproducibility ofthe image is thereby strikingly improved. In case suchhalation-preventing substrate is used, the permissible range of theexposure time (range width of proper exposure time) is broadened and itis possible to obtain a sharp image relief from highlights to shadows.

The fact that a halation-preventing substrate develops such great effectin a planographic printing plate without requiring water having aphotosensitive resin layer on a silicone rubber layer was not recognizedin the prior art. It is well known to provide a halation-preventinglayer beneath a photosensitive resin layer upon applying aphotopolymerizable resin to the production of ordinary relief andlithographic printing plates. However, the present invention is entirelydifferent in structure from the known cases in that ahalation-preventing layer is provided beneath a silicone rubber layersupporting a photosensitive resin layer.

If, as in the prior art, a halation-preventing layer is provided betweena photoadhesive layer and a silicone rubber layer photoadhesion is notrealized and a photoinsolubilized relief easily peels from the siliconerubber layer. The superiority of a halation-preventing base substratebeneath the silicone rubber layer as in the present invention is thusreadily understood.

The halation-preventing base substrate used in the present invention hasadequate flexibility for mounting on an ordinary lithographic press andis strong enough to readily withstand the load normally produced by thelithographic press. As illustrative of such base substrates, thefollowing may be cited:

(1) a metal plate, paper or a plastic sheet provided with ahalation-preventing layer on the surface,

(2) a substantially transparent plastic film provided with ahalation-preventing layer on the back surface, and

(3) paper and plastic film impregnated with or having dispersed thereinan ultraviolet light absorbing agent.

Following is a list of effective ultraviolet light absorbing agents.These ultraviolet light absorbing agents may be dissolved or dispersedin solutions of various polymer binders and applied to the basesubstrate to thereby provide halation-preventing layers.

(1) benzophenone derivatives: 2,2'-dihydroxy-4-methoxy benzophenone,5-chloro-2-hydroxy benzophenone, 4,4'-dimethylamino benzophenone or"Light Absorber DBR" manufactured by Dow Chemical Co. of U.S.A.

(2) benzotriazol derivatives: "Tinuvin P",2-(2'-hydroxy-5'-methyl-phenyl)-benzotriazol and "Tinuvin 320",ingredients not made public.Iadd., .Iaddend.manufactured by Geigy Ltd.of Switzerland.

(3) phenyl salicylate and derivatives thereof: 4-t-butylphenylsalicylate and 4-octylphenyl salicylate,

(4) acrylonitrile derivatives: "Ubinul N-35", ethyl2-cyano-3,3-diphenylacrylate, and "Ubinul .[.530"..].N-539",.[.2-diethylhexyl-2-cyano-3,3-ciphenyl.]..Iadd.2-diethylhexyl-2-cyano-3,3-diphenyl .Iaddend.acrylate,manufactured by Antala Chemical Co. of U.S.A.

(5) other commercially available ultraviolet light absorbing agents,such as: .[."Inhibitor-HRT".]. .Iadd."Inhibitor-HPT,".Iaddend.hexamethyl phosphoric triamine, manufactured by EastmanChemical Co. of U.S.A., "Stouffer Stabilizer-UV928" and "StoufferStabilizer-UV1261", the ingredients of both of which are not madepublic, manufactured by Stouffer Chemical Co. of U.S.A. as well as"C1729" and "AM101", the ingredients of both of which are nickelbisoctyl phenyl sulfide, manufactured by Ferro Chemical Co. of U.S.A.

(6) yellow and red conventional inorganic and organic pigments, theColour Index .[.nunbers.]. .Iadd.numbers .Iaddend.for which are asindicated: Orange Lake CI 77199, Molybdenum Orange, Cadmium Yellow,Yellow Lead, CI 77600.Iadd., .Iaddend.Lead Chromate CI 77601, HansaYellow CI 11670, Chromium Vermillion, CI 77605, Red Lead CI 77578, LakeRed C CI 15585, Chromium Red, Red Iron Oxide CI 77491, Washing Red, BonMaroon CI .[.77766.]. .Iadd.15825, .Iaddend.Vermillion.Iadd.77766.Iaddend., etc.

For the purpose of improving adhesion between such halation-preventingbase substrates and a silicone rubber layer, it is preferable to apply athin (0.05-1.0μ) coating of silicone primer (surface treating agent) tothe surface of said substrate.

As silicone primers used for such purpose, besides commerciallyavailable primers such as "SH 4094", "SH 1200" and "SH 1201", silanecoupling agents such as "SH 6020", "SH 6040" and "SH 6075" may be cited,all manufactured by Toray Silicone Co. of Japan.

The thickness of the silicone rubber layer used in the present inventionis not particularly critical, and is useful in the normal range of0.5-50μ, and preferably 1-10μ.

Useful silicone rubber is obtained by sparsely cross-linking a lineardiorganopolysiloxane (preferably dimethyl polysiloxane) which is a basepolymer. The density of this cross-linking may be expressed by an R/Siratio in the following formula, and in useful silicone rubber, suchdensity is within the range of 1.95-2.10, preferably 1.99-2.01. Arepresentative silicone base polymer has the following repeating unit##STR1## wherein n is an integer not less than 2, R stands for an alkyl,halogenated alkyl, vinyl.Iadd., .Iaddend.aryl or cyanoalkyl group having1-10 carbon atoms, it being preferable that at least 60% of R is methylgroup.

Useful silicone rubber in the present invention is obtained bycondensation reaction of such silicone base polymer and the followingsilicone cross-linking agent

    (1) R--Si--OR').sub.3

    (2) R--Si═(OAc).sub.3

    (3) .[.R--Si--ON--CR'.sub.2).sub.3 .]. .Iadd.R--Si--ON═CR'.sub.2).sub.3 .Iaddend.

wherein R has the same meaning as mentioned above R' stands for an alkylsuch as methyl and ethyl and Ac stands for acetyl group.

Other useful silicone rubbers may be obtained by reaction of theaforesaid base polymer with H-type silicone oil having the followingrepeating unit or addition reaction of the aforesaid base polymers inwhich about 3% of R is vinyl group, or reaction between said H-typesilicone oils. ##STR2## R has the same meaning as mentioned above.

In order to obtain silicone rubber by such cross-linking reaction,besides the aforesaid components, an organometallic carboxylic acid saltof a metal such as tin, zinc, cobalt, lead, calcium and manganese, forexample, dibutyl tin laurate, stannic octoate and cobalt naphthenate ora catalyst like chloroplatinic acid is added.

In order to improve the tenacity of silicone rubber and obtain siliconerubber which can withstand frictional force produced during printing, itis possible to mix a filler with the silicone rubber. Silicone rubberpremixed with a filler is commercially available as silicone rubberstock or silicone rubber dispersion. In case it is preferable to obtainsilicone rubber film by coating as in the present invention, RTV or LTVsilicone rubber dispersion is preferably used. As examples of suchsilicone rubber dispersions, there are silicone rubber dispersions forpaper coating such as "Syl off 23," "SRX-257" and "SH-237" manufacturedby Toray Silicone Co., Ltd. of Japan.

In the present invention, by incorporating a small amount ofphotosensitizer in the silicone rubber layer in addition to theaforementioned components, the effectiveness is greatly enhanced. Byusing such silicone rubber composition, the photoadhesion between thesilicone rubber layer and the photoadhesive layer is remarkablyincreased and it very conveniently provides for achieving the object ofthe present invention. As such photosensitizer for incorporation in thesilicone rubber layer, it is possible to use the same photosensitizer(photoinitiator) which will be contained in a photoadhesive layer to bementioned later. Most particularly, aromatic ketones, especially benzoinalkylethers are conveniently used. As representative examples of suchbenzoin alkylethers, there may be cited benzoin ethyl ether, benzoinisopropyl ether and benzoin butyl ether. Amounts to be contained ofthese photosensitizers are normally 0.1-10% by weight based on the totalweight of the slicone rubber layer.

The thickness of a photopolymerizable adhesive layer used in the presentinvention is not particularly limited, but is normally within the rangeof 0.5-50μ, and preferably 1-10μ.

The following is the composition of such a photopolymerizable adhesivelayer:

(1) at least one kind of photopolymerizable unsaturated compound havinga boiling point above 100° C.

5.0-99.9 parts by weight

(2) photoinitiator

0.1-10.0 parts by weight

(3) heat polymerization inhibitor as occasion demands0.001-.[.0.1.]..Iadd.1.0 .Iaddend.part by weight

(4) polymer or inorganic powder as filler for maintaining thedimensional stability of a photoadhesive layer as occasion demands

0.01-90.0 parts by weight.

The photopolymerizable unsaturated compound referred to herein meansphotopolymerizable unsaturated monomers and oligomers.

As such monomers and oligomers, various compounds may be used. However,it is preferable to make at least one kind of such compound a monomer oroligomer containing at least one hydroxyl group and at least oneacryloyl or methacryloyl group in the same molecule. It is especiallypreferable to make the total concentration of the hydroxyl group and thetotal concentration of the acryloyl group .[.or.]. .Iadd.and.Iaddend.methacryloyl group in the photoadhesive layer at least 0.1mmol/g, respectively. The upper limits of these total concentrations areabout 15 mmol/g, respectively.

By using such monomer of oligomer, the outstanding improvement providedby the present invention in the aforesaid characteristics of adhesivestrength of the ink-.[.respective.]. .Iadd.receptive .Iaddend.imagearea, scratch resistance and high durability in long run printing, ismost effectively realized.

This fact becomes more evident upon comparison with a case in which thetotal concentration of the hydroxyl group and the total concentration ofthe acryloyl and methacryloyl groups are less than 0.1 mmol/g,respectively. Although photoinsolubilization may be achieved in suchcase, the adhesion to the surface of the underlying silicone rubber isinadequate in that the frictional forces generated during developmentprevent the formation of the relief of the image area, or even if therelief is formed it simply peels when it is lightly rubbed with thefinger tip.

The following compounds may be cited as examples of the aforesaidmonomer or oligomer containing at least one hydroxyl group and at leastone acryloyl or methacryloyl group in the same molecule:

(1).[.(metha)crylic.]. .Iadd.(meth)acrylic .Iaddend.acid partial esterof a polyhydric alcohol containing 2-12 carbon atoms,

(2) addition product of active hydrogen compounds having 1-12 carbonatoms such as alcohols, thiols, amines, carboxylic acids, sulfonicacids, phenols, phosphoric acids or hydrogen halide with glycidyl.[.(metha)crylate.]. .Iadd.(meth)acrylate, .Iaddend.

(3) addition product of monoepoxy or polyepoxy compound having 2-14carbon atoms with .[.(metha)crylic.]. .Iadd.(meth)acrylic .Iaddend.acid,

(4) ester of .[.N-methylol(metha)crylamide.]..Iadd.N-methylol(meth)acrylamide .Iaddend.and oxycarboxylic acid having2-10 carbon atoms,

(5) addition product of .[.N-methylol(metha)crylamide.]..Iadd.N-methylol(meth)acrylamide .Iaddend.with monoepoxy or polyepoxycompound having 2-12 carbon atoms,

Of such monomers and oligomers, those having at least 2 acryloyl ormethacryloyl groups and at least 1 alcoholic hydroxyl group arepreferable and those having at least 2 acryloyl or methacryloyl groupsand at least 2 alcoholic hydroxyl groups are most preferable.

Compounds of the aforesaid monomers and oligomers that are especiallyuseful will be listed below, some of which may be used as raw materialfor oligomers useful in the present invention:

(1) .[.(metha)crylic.]. .Iadd.(meth)acrylic .Iaddend.acid partial estersof ethylene glycol, propylene glycol, glycerol, sorbitol, trimethylolmethane, trimethylol ethane, trimethylol propane and pentaerythritol,

(2) adducts of glycidyl .[.(metha)crylate.]. .Iadd.(meth)acrylate.Iaddend.with hydrogen chloride, methanol, ethanol, ethylene glycol,trimethylol methane, pentaerythritol, ethanol amine, triethanol amine,ethane dithiol, methylamine, ethylenediamine, xylylenediamine, aniline,phenylenediamine, acetic acid, .[.(metha)crylic.]. .Iadd.(meth)acrylic.Iaddend.acid, malonic acid, succinic acid, maleic acid, fumaric acid,itaconic acid, malic acid, tartaric acid, citric acid, phenol,thiophenol or hydroquinone,

(3) addition products of glycidyl ester having at least .Badd..[.2l.]..Baddend. 2 epoxy groups and 9-14 carbon atoms with.[.(metha)crylic.]. .Iadd.(meth)acrylic .Iaddend.acid, for example,addition product of .[.(metha)crylic.]. .Iadd.(meth)acrylic.Iaddend.acid with glycidyl esters of phthalic acid, tetrahydrophthalicacid, succinic acid, adipic acid, maleic acid, fumaric acid or itaconicacid.

(4) diester of .[.N-methylol(metha)crylamide.]..Iadd.N-methylol(meth)acrylamide .Iaddend.with malic acid, tartaricacid, and citric acid,

(5) addition product of .[.N-methylol (metha)crylamide.]..Iadd.N-methylol(meth)acrylamide .Iaddend.with glycidyl ester of.[.(metha)crylic.]. .Iadd.(meth)acrylic .Iaddend.acid, phthalic acid,tetrahydrophthalic acid, maleic acid, fumaric acid or itaconic acid.

Aside from the aforementioned .[.(metha)crylic.]. .Iadd.(meth)acrylic.Iaddend.monomers having alcoholic hydroxyl groups, it is possible tocause other ethylenically unsaturated monomers to co-exist as occasiondemands. However, whatever monomers are added, it is preferable that theconcentrations of .[.(metha)cryloyl.]. .Iadd.(meth)acryloyl.Iaddend.group and hydroxyl group as a photoadhesive layer compositionbe kept above 0.1 mmol/g.

It is possible to cause other photopolymerizable monomers or oligomersto co-exist in the photoadhesive layer .[.an.]. .Iadd.as.Iaddend.occasion demands and as representative examples of such monomeror oligomer, there may be cited a .[.(metha)crylic.]..Iadd.(meth)acrylic .Iaddend.acid ester or .[.(metha)crylamide.]..Iadd.(meth)acrylamide .Iaddend.having a boiling point above 100° C.derived from a monohydric alcohol or monovalent amine having not morethan 30 carbon atoms or .[.(metha)crylic.]. .Iadd.(meth)acrylic.Iaddend.acid ester or .[.(metha)-.]. .Iadd.(meth)acrylamide.Iaddend.having a boiling point above 100° C. derived from a polyhydricalcohol or polyvalent amine having not more than 80 carbon atoms, therepresentative examples of such compounds being as follows:

(1) .[.(metha)crylic.]. .Iadd.(meth)acrylic .Iaddend.acid ester of thefollowing alcohols: methanol, ethanol, propanol, pentanol, cyclohexanol,octanol, undecanol, bornyl alcohol, polymethylene glycol, ethyleneglycol, polyethylene glycol, propylene glycol, polypropylene glycol,glycerol, trimethylol methane and pentaerythritol.

(2) .[.(metha)crylamide.]. .Iadd.(meth)acrylamide .Iaddend.derivativesshown below: .[.(metha)crylamide N-methylol(metha)crylamideN-methoxymethyl(metha)crylamide.]. .Iadd.(meth)acrylamide,N-methylol(meth)acrylamide, N-methoxymethyl(meth)acrylamide,.Iaddend.methylene .[.bis-metha)crylamide.]. .Iadd.bis-(meth)acrylamide,.Iaddend.hexamethylene .[.bis-(metha)crylamide.]..Iadd.bis-(meth)acrylamide.Iaddend., diacetoneacrylamide anddihydroxymethyldiacetoneacrylamide.

As representative examples of the photoinitiator which may be used inthe present invention, the following compounds may be cited:

(1) Benzophenone derivatives such as, for example, benzophenone,Michler's ketone, xanthone, anthrone, etc.,

(2) benzoin derivatives such as, for example, benzoin, benzoin methylether, benzoin ethyl ether, etc.,

3) quinones such as, for example, p-benzoquinone, β-methylanthraquinone,etc.

(4) sulfur compounds such as, for example, dibenzyl disulfide,di-n-butyl disulfide, etc.

(5) azo or diazo compounds such as, for example,2-azo-bis-isobutyronitrile, 1-azo-bis-cyclohexane carbonitrile,p-diazobenzylethylaniline, Congo Red, etc.

(6) halogen compounds such as, for example, carbon tetrabromide, silverbromide, α-chloromethylnaphthalene, etc.

(7) peroxides such as, for example, benzoyl peroxide, etc.

(8) uranyl salts such as, for example, uranyl nitrate, etc.

It is possible to select most suitable photoinitiators by taking intoaccount the miscibility with other components of a photoadhesive layerand the spectrum of the light source used for exposure. Generally, thefollowing photoinitiators are most preferable:

Benzophenone, Michler's ketone, xanthone, benzoin methyl ether, dibenzyldisulfide and uranyl nitrate.Iadd.. .Iaddend.

In addition to the aforementioned components it is useful to add a smallamount of heat .[.polymerizable.]. .Iadd.polymerization.Iaddend.inhibitor to the photoadhesive layer for the purpose ofimproving the storability of the printing plate. As representativeexamples of such heat polymerization inhibitor, hydroquinone,phenothiazine, 2,4-dinitrophenol and triphenylmethane may be cited. Itis also possible to add a dye such as Crystal Violet Powder to thephotoadhesive layer so that an exposed area is easily visuallydiscriminated.

Further, it is also possible to mix inorganic powder or polymer with thephotoadhesive layer as occasion demands for the purpose of impartingdimensional stability to the photoadhesive layer and improving adhesionto the silicone rubber.

The printing plate so produced achieves improvement in the storability,scratch resistance and durability of the printing plate in long runprinting.

On the other hand, these additives tend to cause lowering of theconcentration of the .[.(metha)crylic.]. .Iadd.(meth)acrylic.Iaddend.monomer having the hydroxyl group, which is indispensable forthe photoadhesive layer.

Because of such possible adverse effects in the present invention it ispreferable to so control the weights of the additives as to keep themolar concentrations of .[.(metha)cryloyl.]. .Iadd.(meth)acryloyl.Iaddend.group and hydroxyl group derived from a .[.(metha)crylic.]..Iadd.(meth)acrylic .Iaddend.monomer more than 0.1 mmol/g as thephotoadhesive layer composition.

Suitable inorganic powders may usefully be dispersed in thephotoadhesive layer and as representative examples of such powders,colloidal silica, calcium carbonate and titanium dioxide may be cited.

A polymer to be added must have properties of ability to mix uniformlywith other components of the photoadhesive layer, namely, the monomer,oligomer and photoinitiator in a solution or molten state. The desiredcomposition must dissolve or swell in the developing liquid and must beeasily removed in the developing step. The following polymers andcopolymers may be used as the desired polymers provided they have suchproperties. It is possible to mix these polymers and copolymers in theusual manner .[.an.]. .Iadd.as .Iaddend.occasion demands and use theresultant mixtures.

(1) Vinyl polymers or .[.(metha)crylic.]. .Iadd.(meth)acrylic.Iaddend.acid, .[.(metha)crylic.]. .Iadd.(meth)acrylic .Iaddend.acidester polymers and copolymers thereof;

For example, polymers such as polyvinyl alcohol, polyvinyl formal,polyvinyl butyral, or polymers or copolymers of vinyl acetate, vinylchloride, ethylene, vinyl methyl ether, styrene, .[.(metha)crylic.]..Iadd.(meth)acrylic .Iaddend.acid, methylethyl-, cyclohexyl-, benzyl-,2-ethylhexyl-, glycidyl-, 2-hydroxyethyl-, 2-hydroxypropyl-,3-chloro-2-hydroxy-propyl-.[.and.]..Iadd., .Iaddend.dimethylaminoethyl-,2-acid-phosphoxy-ethyl-, 3-chloro-acid-phosphoxyethyl.[.(metha)crylates, and (metha)crylamide, N-methylol(metha)crylamide,N-methoxybutyl(metha)crylamide.]. .Iadd.(meth)acrylates, and(meth)acrylamide, N-methylol(meth)acrylamide,N-methoxybutyl(meth)acrylamide,.Iaddend.hydroxymethyldiacetoneacrylamide, 2-acrylamide-2-methylpropanesulfonic acid.

(2) Unvulcanized rubber such as, for example, natural rubber,polybutadiene, polyisobutylene, polychloroprene, polyneoprene orcopolymers thereof.

(3) Polyethers such as, for example, polyethylene oxide andpolypropylene oxide.

(4) Polyamides such as, for example, copolymers of the followingmonomers: caprolactam, laurolactam, hexamethylenediamine,4,4'-bis-aminocyclohexylmethane, 2, 4, 4-trimethylhexamethylenediamine,isophoronediamine, diglycolic acid, isophthalic acid, adipic acid,sebacic acid, etc.

(5) Cellulose derivatives such as, for example, cellulose acetate,methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, etc.

(6) Polyesters such as, for example, condensation products of phthalicanhydride, maleic anhydride, bis-phenol A, ethylene oxide and propyleneoxide,

(7) Polyurethane such as, for example, polyurethane of hexamethylenediisocyanate, toluene diisocyanate and naphthalene 1, 5-diisocyanatewith 1, 4-butanediol.

(8) Prepolymers of epoxy, urea, alkyd, melamine and phenol resins.

(9) Gum rosin, polyterpene, and cumarone - indene resin.

(10) Other polymers such as, for example, gum arabic and gelatin.

These polymers are selected in combination with the kind of developingliquid used. However, the following compounds are especially useful:

A polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, copolymer of.[.(metha)crylic.]. .Iadd.(meth)acrylic .Iaddend.acid and/or maleicacid, fumaric acid, itaconic acid (0-20 parts by weight) - methylmethacrylate and/or styrene (0-50 parts by weight) -.[.(metha)crylic.]..Iadd.(meth)acrylic .Iaddend.acid ester having 5-20 carbon atoms and/orvinyl acetate (20-100 parts by weight), or copolyamides of nylon 6 -nylon 66 - 2, 2, 4-trimethylhexamethylene diamine 6(1:1:1 by weight) ornylon 6-nylon 66 - 4, 4'diaminocyclohexylmethane 6 (1:1:1 by weight).

As explained above, the base substrate, the silicone rubber layer andthe photoadhesive layer are indispensable elements of a planographicprinting plate according to the present invention. However, the surfaceof the so constituted planographic printing plate is somewhat tacky,tending to cause dust to adhere thereto and thereby posing the problemthat a negative transparency is unlikely to adhere sufficiently close tosaid surface in the exposure step. It may therefore be desirable tointerpose a thin transparent protecting film or to form a protectinglayer on the surface of the photoadhesive layer using a polymersolution. This protecting film also plays a role of inhibiting osmosis(permeation) .[.at.]. .Iadd.of .Iaddend.atmospheric oxygen into thephotoadhesive layer and promoting photopolymerization of thephotoadhesive layer. Such protecting film is useful in the exposurestep, but it is obvious that the protecting film is removed by peelingor dissolution in the developing step and it is unnecessary in theprinting step.

Useful protecting films have transparencies capable of transmittingultraviolet light (ray) having a wave length of 300-400mμ and athickness below 50μ, preferably below 10μ. As representative examples ofsuch useful films layers, the following plastics may be cited:

Polyethylene, polypropylene, polyvinyl chloride, polyvinylidenechloride, polyvinyl alcohol, polyethylene terephthalate and cellophane.

As explained above, a planographic printing plate as a laminateaccording to the present invention may be produced, for example, by thefollowing three methods:

(1) To the base substrate, a silicone rubber dispersion is applied usingordinary coaters such as reverse roll coater, air knife coater andMayerbar coater. In this case, it is possible to pretreat the basesubstrate with silicone primer. Next, the solution of a photoadhesivelayer composition is applied to the silicone rubber layer by the samemethod used in applying the silicone rubber dispersion. In applying thissolution it should not disturb the smooth surface of the silicone rubberlayer. It is possible to add a paint additive of the silicone series ora surface active agent of the fluorine series to said solution forproducing a uniform coating of said solution as occasion demands.

(2) On a peelable carrier sheet, for example,polyethylene,-polypropylene and polyethylene terephthalate films, metalsheets, or silicone coated releasing paper or films, a photoadhesivelayer is formed. The aforesaid photoadhesive layer formed on thepeelable carrier sheet is caused to adhere closely onto a siliconerubber layer provided on the base substrate by the same method as in (1)above. In this case, it is possible to pretreat the surface of saidphotoadhesive layer with silicone primer.

(3) A silicone rubber dispersion is applied to a photoadhesive layerprovided on a peelable carrier sheet by the same method as in (2) above,and sufficiently dried. Additionally, a base substrate is treated withsilicone primer and is caused to closely adhere to the silicone rubberlayer produced previously.

The peelable carrier sheets of (2) and (3) above, may be made protectingfilms per se, but it is also possible to paste on new protecting filmsafter peeling said carrier sheets. Similar good photosensitivity may beobtained using the plate without protecting film, if exposure is madeafter the plate is stored in an atmosphere of gases like nitrogen andcarbon dioxide to expel the dissolved oxygen of the photoadhesive layer.

As a method of providing the protecting film, besides the aforesaid filmlamination, it is possible to use a method of applying a polymersolution like polyvinyl alcohol onto the surface of the photoadhesivelayer or applying said polymer solution onto the peelable carrier sheetto form an oxygen transmission preventing layer in advance, applying thephotoadhesive layer thereon and peeling the peelable carrier sheet at atime when lamination of the silicone rubber layer and the base substrateis completed.

The planographic printing plate of the present invention produced asdescribed in the foregoing, is exposed to actinic light through anegative transparency closely adhered to said plate in vacuo. The lightsource used for this exposure step should generate abundant ultravioletrays (light), and mercury lamps, carbon arc lamps, xenone lamps, metalhalide lamps or fluorescent lamps may be used as such light source.

In the printing plate which has been exposed to light, not only does thephotoadhesive layer of the exposed area harden by photopolymerizationcross-linking reaction, but it also adheres strongly to the underlyingsilicone rubber layer. Therefore, depending upon the kind of theprotecting film and the composition of the photoadhesive layer, when theprotecting film is peeled after exposure, the photoadhesive layer of theunexposed area peels together with the protecting film and only thephotoadhesive layer of the exposed area adheres to the silicone rubberlayer and remains. In such case, the developing operation is completedby merely peeling off the protecting film without resort to use of thedeveloping liquid anew.

It is possible to selectively elute the photoadhesive layer of theunexposed area by immersing the plate in developing liquid or sprayingthe developing liquid thereon after peeling the protecting film.

It is possible to expose or heat the entire surface after development asoccasion demands to strengthen the adhesion between the photoadhesivelayer and the silicone rubber layer and to thereby further improve thedurability in long run printing of the plate.

In the following, the present invention will be explained in furtherdetail by reference to examples. The ethylenically unsaturated monomer(photopolymerizable monomer) and the concentrations of the.[.methacryloyl.]. .Iadd.(meth)acryloyl .Iaddend.group and the alcoholichydroxyl group contained therein used in these examples will be shown inTable 1.

                                      TABLE 1                                     __________________________________________________________________________                                                  .[.(Metha)cryloyl.].                                                          .Iadd.(Meth)acryloyl.Iaddend                                                  .         Alcoholic hy-                                                       group     droxyl group                 Photopolymerizable monomer                                                                      Chemical structural formula                                                                        mmol/g    mmol/g                __________________________________________________________________________    Example 1                                                                            Addition product of 4 mols of GMA/1 mol of xylylenediamine                                       ##STR3##            5.7       5.7                   Example 2                                                                            Addition product of 2 mols of GMA/1 mol of tartaric                                              ##STR4##            4.6       9.2                   Example 3                                                                            Mixture of glycerin monoacry- late with ethylene glycol di-                   acrylate (weight ratio 24:16)                                                                    ##STR5##            8.7       9.1                                            AcrOCH.sub.2 CH.sub.2 OAcr                           Example 4                                                                            Mixture of N-methylolacryl-                                                                     AcrNHCH.sub.2 OH     10.5      5.9                          amide with ethylene glycol di-                                                acrylate.[.(weight).]..Iadd.(weight.Iaddend.                                                    AcrOCH.sub.2 CH.sub.2 OAcr                                  .Iadd.ratio 24:16).Iaddend.                                                   Pentacrythritol diacrylate                                                                      (AcrO).sub.2 C(CH.sub.2 OH).sub.2                                                                  8.1       8.1                          Addition product of 1 mol of                                                                    GOAcr                9.3       4.6                          GMA/1 mol of acrylic acid                                                     Addition product of 1 mol of                                                  GMA/1 mol of N-methylol acryl-                                                                  GOCH.sub.2 NAcr      8.2       4.1                          amide                                                                  Comparative                                                                          Ethylene glycol diacrylate                                                                      AcrOCH.sub.2 CH.sub.2 OAcr                                                                         11.6      0                     Examples                                                                             Trimethylolethane triacrylate                                                                   CH.sub.3 C(CH.sub.2 OAcr).sub.3                                                                    10.8      0                     1 and 2                                                                              Mixture of ethylene bis-acryl-                                                                  AcrNHCH.sub.2 NHAcr  8.6       0                            amide with tetraethylene glycol,                                                                Acr(OCH.sub.2 CH.sub.2).sub.4 OAcr                          .Iadd.diacrylate.Iaddend.                                                     GMA: glycidyl methacrylate                                                                       ##STR6##                                                                      ##STR7##            all based on the entire                                                       monomer                         __________________________________________________________________________

EXAMPLE 1

To an aluminum plate ground by brush, silicone primer "SH 4094 Primer",manufactured by Toray Silicone Co., Ltd. of Japan, was applied to thethickness of 1μ. Onto the resultant film there was applied a siliconegum solution obtained by diluting RTV Silicone Gum Dispersion, "YE 3085"manufactured by Toshiba Silicone Co., Ltd. of Japan with n-heptane andadding to this diluted silicone gum dispersion benzoin ethylether in anamount of 3% by weight, calculated as solid, and the resultant appliedsilicone gum solution was dried by air to provide a 5μ thick siliconegum layer. This silicone gum was a linear diorganopolysiloxane havingacetoxy end group at which cross-linking could be produced by the actionof atmospheric moisture through emitting acetic acid to give arubber-like-coating. The foregoing assembly will be termed the base andsilicone gum layer.

Additionally, a 2μ thick photoadhesive layer was applied on a 9μ thickpolypropylene film "Torayfan" manufactured by Toray Industries, Inc. ofJapan, the photoadhesive layer having the following composition.

    ______________________________________                                        (a) Addition product of 4 mols of glycidyl methacry-                          late with 1 mol of xylylenediamine                                                                        95% by                                                                        weight                                            (b) Benzoin methylether     5% by                                                                         weight                                            ______________________________________                                    

Next, the base and silicone gum layer and the photoadhesive layer wereso pressed together that the surface of the silicone rubber layer was incontact with and adhered closely to the surface of the photoadhesivelayer to produce a presensitized planographic printing plate.

On this planographic printing plate, a negative transparency was appliedand the two were caused to adhere closely to each other in vacuo. Thiswas then irradiated from a distance of 10 cm for 3 minutes by light froma fluorescent lamp (FL20S-BL360, manufactured by Mitsubishi ElectricCo., Ltd. of Japan).

When the "Torayfan" was peeled and the printing plate was then immersedin a 50% aqueous solution of isopropanol and lightly rubbed, thephotoadhesive layer of the unexposed area was easily removed, whereas,at the same time the photoadhesive layer of the exposed area wasphoto-insolubilized and adhered strongly to the underlying siliconerubber layer so that a tenacious image relief remained.

By so doing, a planographic printing plate was obtained whichcorresponded to the image of the negative transparency throughout theentire printing plate. When this printing plate was mounted on a rotaryoffset duplicator, "Multilith 1250" manufactured by AddressographMultigraph Co. and printed out using a printing ink, "Dricolor Black"manufactured by Dainippon Ink and Chemicals, Inc. of Japan, withoutusing water for moistening, excellent printed matter was obtained. Theprinting press of this example had good image reproducibility and wascapable of printing more than 10,000 copies.

EXAMPLE 2

On a crude aluminum plate whose surface had not been treated, a 2μ thickhalotion-preventing layer of the following composition was provided.

(a) Styrene--acrylic acid (90:10 weight ratio) copolymer (intrinsicviscosity in cellosolve acetate: 0.3)

95 parts by weight

(b) Michler's ketone--5 parts by weight

Next, to the surface of said halation-preventing layer, a 1% heptanesolution of silicone primer "SH 4094" manufactured by Toray SiliconeCo., Ltd. of Japan, was applied and dried.

Additionally, on a 9μ thick "Torayfan" polypropylene film, a 5μ thickphotoadhesive layer having the following composition was provided.

(a) Copolyamide (a nylon 6--nylon 66 - 2, 2, 4-trimethylhexamethylenediamine adipate (30:35:35 by weight) copolymer--37% byweight

(b) Addition product of 1 mol of tartaric acid with 2 mols of glycidylmethacrylate 60% by weight

(c) Benzophenone--3% by weight

(d) Phenothiazine--0.01% by weight

Onto this photoadhesive layer, a .[.colution.]. .Iadd.solution.Iaddend.obtained by diluting with n-heptane, a heat-curing typesilicone gum, "SH 7023" manufactured by Toray Silicone Co., Ltd. ofJapan, and adding to the resultant diluted silicone gum dispersion,benzoin ethyl ether in an amount of 3% by weight calculated as solid,was applied and dried by air.

Next, this laminar assembly of "Torayfan," photoadhesive layer andsilicone gum was applied under pressure to the aforesaid coated aluminumbase plate with the surface of the silicone primer adhering closely tothe surface of the silicone gum and thereafter the whole was heated at100° C. for 15 minutes, forming a presensitized planographic printingplate.

On the presensitized planographic printing plate so obtained, a negativetransparency was applied and caused to adhere closely to said printingplate in vacuo, and was then irradiated for 2 minutes by light from ahigh pressure mercury lamp (ORC Jet Light 3000, at a distance of 1 m).The "Torayfan" was peeled off and thereafter the photoadhesive layer ofthe unexposed area was eluted by washing with modified ethanol. Whenprinting was carried out similarly as in Example 1, good printed matterwas obtained.

EXAMPLE 3

On a crude aluminum plate, a halation-preventing layer and a siliconeprimer layer were provided similarly as in Example 2, comprising a baselayer. Additionally, on a 9μ thick polyethylene terephthalate film,"Lumirror" manufactured by Toray Industries, Inc. of Japan, there wasapplied a 1μ thick layer of .[."Gosenil.]. .Iadd."Gosenol .Iaddend.GH17", a polyvinyl alcohol manufactured by Nippon Gosei Kagaku Co., Ltd.of Japan, on which a 2μ thick photoadhesive layer having the followingcomposition was provided.

(a) Ethyl acrylate--methyl methacrylate--acrylic acid (70:20:10 weightratio) copolymer (intrinsic viscosity in cellosolve acetate 0.4)--55% byweight

(b) Glycerol monoacrylate--24% by weight

Ethylene glycol .[.dia.]. .Iadd.diacrylate.Iaddend.--16% by weight.[.crylaye.].

(c) Michler's ketone--5% by weight

To the surface of this photoadhesive layer was applied a solutionobtained by diluting a silicone gum, "SH 9732," manufactured by ToraySilicone Co., Ltd. of Japan, with Naphtha No. 3 (manufactured by Esso)and this solution was then dried by air.

Next, the base layer and the foregoing composite photoadhesive andsilicone gum layer were so pressed together that they adhered closely atthe interface between the surface of the silicone primer and the surfaceof the silicone gum, and the assembly thereafter allowed to standundisturbed for 24 hours.

The photosensitive planographic printing plate so obtained was at firstdenuded of the covering film to expose the polyvinyl alcohol layer onthe surface of the printing plate and a negative transparency was placedon the surface of the polyvinyl alcohol layer, and exposed to light thesame as in Example 2. The printing plate which had been exposed to lightwas easily developed by an aqueous solution of 0.2 N-sodium hydroxideand a strong ink-receptive image relief was produced on the surface ofthe silicone rubber.

EXAMPLE 4

Example 3 was repeated except that in producing the planographicprinting plates the monomer components (b) of the photoadhesive layerwere replaced by the following compounds,

(a) N-methylolacrylamide--24% by weight

Ethylene glycol diacrylate--16% by weight

(b) Pentaerythritol diacrylate--40% by weight

(c) Addition product of 1 mol of acrylic acid with 1 mole of glycidylmethacrylate--40% by weight

(d) Addition product of 1 mol of N-methylolacrylamide with 1 mol ofglycidyl methacrylate--40% by weight

When planographic printing plates produced in accordance with thisexample were exposed to light and developed the same as in Example 3,image relief strongly adhering to the surface of the silicone rubberlayer were obtained in each case.

Comparative Example 1

Example 3 was repeated except for replacing the photopolymerizablemonomer components (b) of the photoadhesive layer by the followingphotopolymerizable monomers not containing alcoholic hydroxyl groups.

(a) Ethylene glycol diacrylate--40% by weight

(b) Trimethylolethane triacrylate--40% by weight

(c) Methylenebisacrylamide--20% by weight

Triethylene glycol diacrylate 20% by weight

In each case of this comparative example, a relief of the image portiondid not strongly adhere to the surface of the silicone rubber layer, butpeeled off during the developing .[.opertion.]. .Iadd.operation.Iaddend.or were peeled off by inking rollers upon printing severalhundreds of copies, to give incomplete printed matters.

Comparative Example 2

Example 3 was repeated except for replacing the polymer component (a) ofthe photoadhesive layer by the following polymers having alcoholichydroxyl groups and replacing the photopolymerizable monomers of (b) ofthe photoadhesive layer by the photopolymerizable monomers notcontaining alcoholic hydroxyl groups used in Comparative Example 1.

(a) 40% saponified product of polyvinyl acetate

(b) Ethyl acrylate--styrene--2-hydroxyethylmethacrylate--acrylamide--acrylic acid (64:14:12:2:8 weight ratio)copolymer (intrinsic viscosity in cellosolve acetate 0.3).

(c) Poly-2-hydroxypropyl methacrylate (intrinsic viscosity in cellosolve0.2).

As a result of using any one of the above polymers of this comparativeexample, the adhesion between the image relief and the surface of thesilicone rubber layer was very inferior similarly as in ComparativeExample 1.

The following is claimed:
 1. A negative acting presensitized dryplanographic printing .[.place.]. .Iadd.plate .Iaddend.comprising:(a) aflexible base layer, (b) a sparsely cross-linked lineardiorganopolysiloxane layer overlying said base layer, and (c) aphotoadhesive layer overlying said diorganopolysiloxane layer, and indirect contact therewith comprising at least one photopolymerizableunsaturated compound having a boiling point above 100° C. and aphotoinitiator wherein at least one said photopolymerizable compound hasat least one hydroxyl group and at least one acryloyl group or onemethacryloyl group in the same molecule and the total concentration ofthe hydroxyl groups and the total concentration of the acryloyl .[.or.]..Iadd.and .Iaddend.methacryloyl groups in the photoadhesive layer areeach greater than 0.1 mmol/g.
 2. The negative-acting presensitized dryplanographic printing plate of claim 1, wherein at least one kind ofsaid photopolymerizable unsaturated compound is a member selected fromthe group consisting of(a) partial esters of acrylic and/or methacrylicacid with polyhydric alcohols having 2-12 carbon atoms, (b) additionproduct of glycidyl acrylate and/or methacrylate with hydrogen halides,alcohols, thiols, amines, carboxylic acids, sulfonic acids, phenols andphosphoric acids having 1-12 carbon atoms, (c) addition products ofacrylic and/or methacrylic acid with epoxy compounds having 2-14 carbonatoms, (d) esters of N-methylolacrylamide or methacrylamide withoxy-carboxylic acids having 2-10 carbon atoms, (e) addition products ofN-methylolacrylamide or methacrylamide with epoxy compounds having 2-12carbon atoms.
 3. The negative-acting presensitized dry planographicprinting plate of claim 1, wherein at least one kind of the saidphotopolymerizable compound is a member selected from the groupconsisting of(a) partial esters of acrylic and/or .[.methaacrylic.]..Iadd.methacrylic .Iaddend.acid with ethylene glycol, propylene glycol,glycerol, trimethylol methane, trimethylol ethane, trimethylol propane,sorbitol and pentaerythritol, (b) addition products of glycidyl acrylateor methacrylate with hydrogen chloride, methanol, ethylene glycol,trimethylol methane, pentacrylthritol, ethanolamine, trimethanolamine,ethane dithiol, methylamine, ethylenediamine, xylylenediamine, aniline,phenylenediamine, acetic acid, acrylic acid, methacrylic acid, malonicacid, succinic acid, maleic acid, fumaric acid, itaconic acid, malicacid, tartaric acid, citric acid, phenol, thiophenol and hydroquinone,(c) addition products of acrylic and/or methacrylic acid with diglycidylesters derived from the group consisting of phthalic acid,tetrahydrophthalic acid, succinic acid, adipic acid, maleic acid,fumaric acid and itaconic acid, (d) diesters of N-methylolacrylamide ormethacrylamide with malic acid, tartaric acid, and citric acid, and (e)addition products of N-methylolacrylamide or methacrylamide withglycidyl esters of acrylic acid, methacrylic acid, phthalic acid,tetrahydrophthalicacid, maleic acid, fumaric acid and itaconic acid. 4.The negative-acting presensitized dry planographic printing plate ofclaim 1, wherein a halation preventing layer is interposed between saidbase layer and said diorganopolysiloxane layer such that less than 20%of the ultraviolet light of the wave length from 300 to 400 mμ isreflected.
 5. A negative-acting presensitized dry planographic printingplate comprising:(a) a flexible base layer, (b) a sparsely cross-linkedlinear diorganopolysiloxane layer overlying said base layer, (c) aphotoadhesive layer overlying said diorganopolysiloxane layer,comprising at least one photopolymerizable unsaturated compound having aboiling point above 100° C. and a photoinitiator, wherein at least onekind of said photopolymerizable compound has at least one hydroxyl groupand at least one acryloyl group or one methacryloyl group in the samemolecule and the total concentration of the hydroxyl group and the totalconcentration of the acryloyl .[.or.]. .Iadd.and .Iaddend.methacryloylgroups in the photoadhesive layer are each greater than 0.1 mmol/g, and(d) a polymeric layer overlying said photoadhesive layer, capable oftransmitting light of wave length from 300 to 400 mμ and protecting saidphotoadhesive layer from oxygen.
 6. The method of preparing thenegative-acting presensitized plate of claim 5 which comprises the stepsof applying said photoadhesive layer on said polymeric layer andlaminating said layers on said diorganopolysiloxane layer previouslyapplied on said base layer with said photoadhesive layer in contact withsaid diorganopolysiloxane layer.
 7. The method of preparing thenegative-acting presensitized plate of claim 5, which comprises thesteps of applying said diorganopolysiloxane layer on said photoadhesivelayer previously applied on said polymeric layer and laminating saidlayers on said base layer with said diorganopolysiloxane layer incontact with said base layer.
 8. The negative-acting presensitized plateof claim 1, wherein said diorganopolysiloxane layer incorporates aphotosensitizer in the range of 0.1-10% by weight based upon the totalweight of the silicone rubber layer.
 9. The negative-actingpresensitized .[.film.]. .Iadd.plate .Iaddend.of claim 1, wherein saidphotoadhesive layer consists essentially of(a) said photopolymerizableunsaturated compound 5.0-99.0 parts by weight, (b) a photoinitiator0.1-10.0 parts by weight, (c) a heat polymerization inhibitor 0.001-1.0parts by weight, and (d) a filler for maintaining dimensional stabilityof said photoadhesive layer 0.01-90.0 parts by weight.
 10. Thenegative-acting presensitized plate of claim 5, having ahalation-preventing layer between said base layer and saiddiorganopolysiloxane.
 11. The method of preparing the negative-actingpresensitized plate of claim 10 which comprises the steps of applyingsaid halation-preventing layer on said base layer, applying saidphotoadhesive layer on said polymeric layer, applying saiddiorganopolysiloxane .[.gum.]. layer on said photoadhesive layer,laminating said layers together under pressure with saidhalation-preventing layer in contact with said diorganopolysiloxanelayer.
 12. The negative acting dry planographic printing plate of claim1, wherein the surface of said photoadhesive layer in contact with saiddiorganopolysiloxane layer has been pre-treated with silicone primer.13. The negative acting presensitized dry planographic printing plate ofclaim 5, wherein the surface of said photoadhesive layer in contact withsaid diorganopolysiloxane layer has been pre-treated with siliconeprimer.
 14. A negative acting presensitized dry planographic printingplate comprising:(a) a flexible base layer of polyethyleneterephthalate, (b) a halation .[.prevention.]. .Iadd.preventing.Iaddend.layer on said base layer and comprising a styrene-acrylic acidcopolymer and .[.a photoinitiator.]. .Iadd.an .Iaddend.ultraviolet lightabsorbing agent (c) a sparsely cross-linked linear diorganopolysiloxanelayer overlying said styrene-acrylic acid copolymer layer, (d) aphotoadhesive layer overlying said .[.diorganosiloxane.]..Iadd.diorganopolysiloxane .Iaddend.layer consisting of a compositioncomprising(1) an .[.ethylacrylate-methylmethacrylate-acrylic.]..Iadd.ethyl acrylate-methyl methacrylate-acrylic .Iaddend.acidcopolymer, (2) the addition product of 4 mols of glycidyl methacrylatewith 1 mol xylylenediamine and ethyleneglycol diacrylate, said additionproduct containing hydroxyl groups and .[.acryloyl or methacryloyl.]..Iadd.methacryloyl .Iaddend.groups and (3) a photoinitiator; the totalconcentration of the hydroxyl group and the total concentration of theacryloyl .[.or.]. .Iadd.and .Iaddend.methacryloyl groups in thephotoadhesive layer each being greater than 0.1 mmol/g., and then, (e) alayer of .[.diorganopolysiloxane.]. .Iadd.polypropylene .Iaddend.capableof transmitting light having a wavelength from 300 to 400 mμ.